When using an external keyboard, how can use a function key as a function key (e.g. F10) instead of Mac custom control button (e.g. mute)? The built-in keyboard contains an fn button, but I cannot find it in the external one.

If you are using a Mac keyboard, there should be a Fn key. On the latest Mac wired slim aluminium keyboard, it is around the home, page up, page down area. On the wireless slim keyboard, it is to the bottom left.

When taking a screenshot of a single window in OS X, pressing command shift 4 space will allow you to capture the single window with it's drop shadow, without any other apps in the background.
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David PearceSep 18 '09 at 8:42